In the nanometer range, complex, free-standing 3D architectures are very difficult to produce in a single step due to the required precision. In the Christian Doppler Laboratory for Direct Write Fabrication of 3D Nano-Probes, scientists at Graz University of Technology are therefore devoting themselves to the fundamentals of 3D Nanoprinting to push its possibilities beyond current limitations.
For that, the research group uses the technology Focused Electron Beam Induced Deposition (FEBID), which is already used successfully in the production of complex but often flat nanostructures.
Examples from the three-dimensional printed nanoworld show the complexity (a), the achievable structure sizes (b) as well as the path from meshed towards closed 3D surfaces (c). All images are re-coloured scanning electron microscope micrographs with a 500 nm wide scale bar.
Image: Harald Plank, Institute of Electron Microscopy and Nanoanalysis at TU Graz
On the other hand, it also enables fabrication on uneven or rough surfaces. "This type of 3D nanoprinting opens up completely new playgrounds for science and industry," says Harald Plank from the Institute of Electron Microscopy and Nanoanalysis at TU Graz and head of the CD lab.
With the new technology, future challenges can be mastered that are barely possible with alternative nanofabrication methods such as electron beam lithography. "With this method, it would also be possible to produce 3D nanostructures on a pencil tip in a single step, which is very difficult to do with alternative technologies," explains Plank.
"The printing process takes place in the vacuum chamber of electron microscopes. The functional gases are introduced with a fine capillary in close proximity to the sample. The gaseous molecules then adsorb on the surface and are chemically broken down and immobilised by the focused electron beam they remain in place through interaction with the electrons," explains Plank. "You can imagine 3D nanoprinting like a ballpoint pen: The electron beam acts like a ballpoint pen refill and the gas is the ink.
Plank and his team were inspired by Lego bricks for printing inclined structures: "To build a tilted architecture using Lego, the next higher layer of bricks must always be moved sideward. This is exactly what we have transferred to 3D nanoprinting: Before applying the next layer, we shift the electron beam and literally print diagonally upwards."
Plank and his team are satisfied with the result: "Small series production will start in Vienna in the coming months and open up new possibilities for the industrial partner GETec Microscopy.”
This project also focuses on extending the process to 3D surfaces and multi-material structures, which further increases the design flexibility and thus the relevance of this technology in research and development.
TU Graz. Posted: Accessed: Nov 17, 2019.